1. Field of the Invention
This invention relates to a TIG (Tungsten Inert Gas) welding equipment, and more particularly to a welding equipment suitable for performing semi-automatic hot wire TIG arc welding.
2. Description of the Prior Art
FIG. 1 is a drawing showing one example of automatic TIG welding of the conventional techniques, wherein an arrangement of the hot wire TlG welding equipment is shown which feeds a filler wire while energizing and heating it. An arc power source 3 for d-c welding is connected to a Tungsten electrode 1 and a base metal 2, and an arc 4 is formed in argon-shield-gas with the Tungsten electrode 1 being the negative electrode. The filler wire 5 is fed from a wire feeding device 6, passed through a conduit 7 and a wire guide 9 including a contact tip 8 connected to the conduit 7, led to an arc generating section, and brought into contact with a base metal 2. In this case, a wire power source 10 is connected to a section between the contact tip 8 and the base metal 2, and direct current or alternating current is fed to the filler wire 5 to initiate Joule heat, whereby the filler wire 5 is increased in melting rate.
Now, in performing the ordinary manual TIG welding, when deposited metal is needed, a welding rod (e.q. diameter: 2 mm and length: 600 mm) is held in the left hand, and a TIG arc torch is held in the right hand, whereby welding is performed while the metal to be deposited is manually supplied. On the other hand, in performing the automatic TIG welding, the filler metal is supplied by a wire feeding device for automatically feeding the filler wire by use of a motor. Both the wire guide and the TIG arc torch are fixedly held by a stand, which is mounted onto a welding carriage for welding.
A semi-automatic TIG welding is known as one which lies between the two welding methods described above. FIG. 2 shows a semi-automatic TIG welding torch on the market. This torch is constructed such that the wire guide 9 is half-fixedly secured to a portable TIG torch body 11 and the filler wire 5 is automatically fed at a predetermined rate by a wire feeding device. Since the forward end of the filler wire 5 needs to be fed to a proper position in a molten pool 12 formed by the arc 4, the TIG torch body 11 is provided thereon with an adjustor 13 for finely adjusting the filling position. A welder controls a knob in a remote control box of the wire feeding device by the left hand to adjust the wire feed rate, while holding a torch 14 in the right hand and adjusting the position of the torch. In the case of the cold wire method wherein the wire 5 is not energized and heated, normally, the filler wire 5 is fed from a direction proceeding the welding. Whereas, in the hot wire method wherein the filler wire 5 is energized and heated, the filler wire 5 is fed from behind relative to the direction of welding.
Now, in the welding method illustrated in FIG. 2, to change the direction of welding during welding, it is necessary to change a wire filling position as well. This can be done only if the adjustor 13 is adjusted by left hand to adjust the filling position of the filler wire 5. However, while the TIG arc 4 needs a delicate control on the arc length, it is extremely difficult to carry out both the delicate control and the aforesaid adjustment at the same time. After all, the adjustor 13 cannot be used during welding. In consequence, it is unavoidable that the torch is operated such that the welding torch 14 as a whole is changed in direction to change the direction of welding. Furthermore, in order to obtain the proper welding conditions by use of the torch 14 shown in FIG. 2, it is necessary that the position where the forward end of the filler wire 5 enters the molten pool 12 is held at the optimal position. However, when an angle formed between the torch 14 and the base metal 2 is varied, the position where the forward end of the filler wire 5 enters the molten pool 12 is varied to a considerable extent. After all, the angle of holding the torch 14 should be held constant.
As described above, in the semi-automatic TIG welding, wherein the wire guide 9 is fixed to the TIG torch body 11, the torch 14 is restricted in its movement and the freedom in the welding operations is considerably hampered, after all. Then, when the wire guide 9 is separated from the TIG torch body 11, and welding is to be performed while the TIG torch body 11 is held in the right hand and the wire guide 9 is held in the left hand, such disadvantages are presented that the both hands have been already occupied and the remote control operations such as adjustment of feeding rate of the filler wire 5 and regulation of the arc current cannot be carried out.
From the above-described reasons, it is practical to use the torch 14, wherein the torch body 11 and the wire guide 9 as shown in FIG. 2 are integrally formed and capable of being held by one hand. However, the controllability of the torch 14 is not good. In consequence, the semiautomatic TIG welding has not been widely adopted, while it has a great need.